/**
 * Copyright 2010 Nicholas Alexander Cross
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.dataporter.io;

import org.apache.commons.lang.NullArgumentException;

import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.InputStream;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

public class FileEntitySource implements EntitySource<InputStream> {

    private final Map<String, File> inputFiles;
    private final ArrayList<String> entityNames;

    public FileEntitySource( String entityName, File inputFile ) {
        this( _fileMap( entityName, inputFile ));
    }

    private static Map<String, File> _fileMap( String entityName, File inputFile ) {
        HashMap<String, File> fileMap = new HashMap<String, File>();
        fileMap.put( entityName, inputFile );
        return fileMap;
    }

    public FileEntitySource( Map<String, File> inputFiles ) {
        this.inputFiles = inputFiles;

        if ( inputFiles == null )
        {
            throw new NullArgumentException( "inputFiles" );
        }

        entityNames = new ArrayList<String>();
        entityNames.addAll( inputFiles.keySet() );
    }

    public InputStream sourceForEntity( String entityName ) {
        try
        {
            File file = inputFiles.get( entityName );

            if ( file != null )
            {
                return new FileInputStream( file );
            }
            else
            {
                throw new IllegalStateException( "No file for entity: " + entityName );
            }
        }
        catch ( FileNotFoundException e )
        {
            throw new IllegalStateException( "File for entity doesn't exist at location", e );
        }
    }

    public List<String> entityNames() {
        return entityNames;
    }

}
